JP2949982B2 - Processing method of magnetic gap depth of thin film magnetic head - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for processing a magnetic gap depth of a thin film magnetic head used in a magnetic recording / reproducing apparatus.

[0002]

2. Description of the Related Art Since the recording / reproducing characteristics of a magnetic head are strongly affected by the magnetic gap depth, it is necessary to finish the magnetic gap depth to a very small size of 0 to 1 μm in grinding and polishing.

A method of processing the depth of the magnetic gap of a conventional thin film magnetic head will be described below.

In order to terminate the grinding / polishing at a predetermined magnetic gap depth, the grinding / polishing amount as shown in FIG. 4 is provided at both ends of a magnetic head block 1 in which a plurality of thin film magnetic heads are arranged in a straight line. A method of performing processing while measuring using an optical microscope or the like the size of the end face from which the marker 9 has been removed by grinding and polishing, or a thin film magnetic head itself or
A method in which markers having the same magnetic gap depth are formed, and their sections are processed while measuring the magnetic gap depth using an optical microscope or the like, or as shown in FIG. A magnetic gap depth monitor element 4 is formed at both ends, and grinding and polishing are performed while supplying a direct current to the magnetic gap depth monitor element 4. As a result, as the magnetic gap depth monitor element 4 is partially removed, the magnetic gap depth monitor element 4 is removed. There is a method of processing to a predetermined magnetic gap depth utilizing the change in the resistance value of the monitor 4.

[0005]

However, the above-mentioned conventional method has a problem that the processing must be temporarily interrupted in order to determine the magnetic gap depth during the processing, and that the marker 9 for determining the amount of grinding and polishing has to be used. There was a problem that a reading error occurred in the measurement because the dimensions were minute.

Further, in the method of supplying a direct current to the magnetic gap depth monitor element 4, a resistance change occurs at a contact connecting the magnetic gap depth monitor element 4 and an electric circuit, or it occurs during grinding and polishing. The resistance value of the magnetic gap depth monitor element 4 fluctuates due to a change in heat or outside air temperature, or a lapping machine made of a metal such as a grindstone or tin contacts the magnetic gap depth monitor element 4 during grinding and polishing. There is noise ingress resulting from
Therefore, when processing a plurality of thin-film magnetic heads or a magnetic head block 1 in which a plurality of thin-film magnetic heads are arranged in a straight line, it is difficult to precisely process the gap depth of each magnetic head to a predetermined size. There was a problem that there is.

The present invention solves the above-mentioned conventional problems, and provides a method of processing the magnetic gap depth of a thin film magnetic head which can finish the magnetic gap depth of a thin film magnetic head or a magnetic head block with high accuracy and efficiency. The purpose is to do.

[0008]

In order to achieve this object, a method of processing the magnetic gap depth of a thin-film magnetic head according to the present invention comprises applying a high-frequency signal to a magnetic gap depth monitor element during grinding and polishing. In this method, noise is reduced by a circuit that removes low-frequency components from the output signal, and processing is terminated when the output signal reaches a predetermined level.

[0009]

According to this method, unnecessary noise is removed from the output signal from the magnetic gap depth monitor element by passing the signal through a circuit for removing low-frequency components. Will be detected.

[0010]

An embodiment of the present invention will be described below with reference to the drawings. As shown in FIGS. 1 and 2, a magnetic head block 1 in which magnetic heads having a magnetic gap depth m larger than a predetermined magnetic gap depth d are aligned, and a magnetic head block fixing jig for fixing the magnetic head block 1 2
The slider processing surface 3 is ground and polished to perform magnetic gap depth processing.

The magnetic gap depth machining is performed on the magnetic head by removing the slider machining surface 3 of the magnetic head having a magnetic gap depth m larger than a predetermined magnetic gap depth d by grinding / polishing. This is a process to give satisfactory magnetic properties.

At both ends of the magnetic head block 1, there are formed magnetic gap depth monitoring elements 4 whose part is removed by grinding / polishing at the same time as the magnetic head during magnetic gap depth processing. 10 is a lead wire for applying a high-frequency signal to the magnetic gap depth monitoring element 4;
1 and 12 are cores, 13 is a coil, 14 and 15 are insulating layers,
16 is a protective layer.

As shown in FIG. 3, the detecting device 8 includes a magnetic gap depth monitoring element 4, an AC oscillator 5 for generating a high frequency signal several to several tens times the commercial frequency, and a magnetic gap depth monitoring device. A noise removal circuit 6 is applied to the monitor element 4 and detects only a high-frequency output signal from the monitor element 4, and a signal detector 7 detects the end of the magnetic gap depth processing based on the output signal.

A processing method using the detecting device 8 and a grinding / polishing machine will be described below. A high frequency signal from the AC transmitter 5 is applied to the magnetic gap depth monitor 4. Since a part of the magnetic gap depth monitor element 4 is removed by the grinding and polishing performed in the magnetic gap depth processing, the electric resistance increases, and the level of the output signal changes with respect to the input signal. I do. At the same time, since the magnetic gap depth monitor element 4 is always in contact with a lapping machine made of a metal such as a grindstone or tin, low frequency noise is included in the output signal from the magnetic gap depth monitor element 4. It is mixed. Therefore, a noise removal circuit 6 that removes low frequency signals from the output signal and detects only useful high frequency signals is used. Further, the amplitude of the output signal changes during processing of the magnetic gap depth of the magnetic head, and the amplitude decreases to a predetermined level by the signal detector 7 configured with a Wheatstone bridge for detecting the output of the high-frequency signal. At this point, a processing end point that is a predetermined magnetic gap depth can be detected.

When the processing is completed, a magnetic head having a predetermined magnetic gap depth is set to ± 0.2 of the target size.
It can be manufactured with a high accuracy up to 5 μm and a good yield.

Further, since it is not necessary to temporarily suspend the processing for checking the magnetic gap depth during the processing of the magnetic disk depth, the processing capacity is improved and the number of steps can be reduced.

[0017]

As is clear from the above description of the embodiment, the present invention applies a high frequency signal to the magnetic gap depth monitor element during grinding / polishing and removes a low frequency from the output signal. An excellent thin-film magnetic method that finishes the magnetic gap depth of a thin-film magnetic head or a magnetic head block with high precision and efficiency by reducing noise with a circuit that performs processing and terminating processing when the output signal reaches a predetermined level. It is possible to realize a magnetic gap depth machining method for a head.

[Brief description of the drawings]

FIG. 1 is an external perspective view showing a state in which a magnetic head block is fixed to a fixing jig in a method of processing a magnetic gap depth of a thin film magnetic head according to one embodiment of the present invention.

FIG. 2 is a schematic cross-sectional view of a main part constituting a magnetic gap of the thin-film magnetic head.

FIG. 3 is a circuit diagram of a method for processing the magnetic gap depth of the thin-film magnetic head according to one embodiment of the present invention;

FIG. 4 is an external perspective view showing an enlarged main part of a magnetic head block in a conventional method of processing the magnetic gap depth of a thin film magnetic head.

FIG. 5 is an external perspective view showing an enlarged main part of a magnetic head block in another conventional processing method of the magnetic gap depth of a thin film magnetic head.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Magnetic head block 4 Magnetic gap depth monitor element 5 AC oscillator 8 Detector

Claims (1)

(57) [Claims] 1. A processing method for grinding and polishing a plurality of thin film magnetic heads or a magnetic head block in which a plurality of thin film magnetic heads are arranged in a straight line so as to have a predetermined magnetic gap depth. A high-frequency signal is applied to a magnetic gap depth monitoring element formed in advance near the magnetic head, noise is reduced by a circuit that removes a low frequency from the output signal, and when the output signal reaches a predetermined level, A method of processing the magnetic gap depth of the thin-film magnetic head to finish the processing.